For some reason, when calling `showModal`, `useMemo` in modal.js and the code for the modal component (here: <Invoice>) is called twice.
This leads to the `onSuccess` callback being called twice and one failing since the first one deletes the invoice.
Our invoice IDs can be enumerated.
So there is a - even though very rare - chance that an attacker could find a paid invoice which is not used yet and use it for himself.
Random payment hashes prevent this.
Also, since we delete invoices after use, using database IDs as proof of payments are not suitable.
If a user tells us an invoice ID after we deleted it, we can no longer tell if the invoice was paid or not since the LN node only knows about payment hashes but nothing about the database IDs.
ekzyis